Electrical apparatus



May 22, 1928.

H. A. THOMPSON I ELECTRICAL APPARATUS Original Filed July 29, 1926 INVENTOR 2 7 6?, .WM/Hw-u am-W M da-M Patented May 22, 1928.

' ouirsn stares TION OF PE'NNSYLVANIAQ rsae- HOWARDA. THOMPSON, 0F EDG'EWQODBOROUGH, PENNSYLVANIA, ASSTGNOR TO "JIHEv UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A'ODRPORA wens ELECTRICAL APPARATUS. I

Application and July as, 1926,1Seria1 No. 125,680. Renewed ma 10, 1927.

My invention relates to electrical apparatus, and particularly to apparatus forsupplying currents of different frequencies from two sources to a single load such asthe rails of a stretch of railway track. p

One object of the invention is the provision, in apparatus of the type described, of means for preventing the how of current from one source through'the other source.

I will describe one form of apparatus embodying my invention, and'will then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view "illustrating one form of apparatus embodying my invention.

Referring to the drawing, the reference characters 1 and l -designate the track rails of a stretch of railway track over which traific normally, moves in "the direction indicated by the arrow. 'These'trackrails'are divided, by meansof insulated joints 2, into a plurality of successive track sections A 13, BC, etc. Each track section is provided with a track transformer designated by thereference character T with an "exponent corresponding to the location and having a secondary 5 connected across the 'rails ;ad jacent the exit end of the "corresponding" section through the usual impedance '7'. The primary 6 of each transformer T is constantly supplied with alternating current from a suitable source such as an"'alternat0r Kfoverflin'e wires 3 and3.

Each track section is "further provided with'a track relay designated by the reference character R with a suitable exponent and connected across'the .rails adjacent the entrance 'end of the correspondingsection. Eachtrack relay R is responsive to the'track circuit current supplied to the rails of the associated section by transformer'Tat the exit end of such section. The track relays R may be utilized in any desired manner to control trackway governing apparatus not shown in'the drawing. Means are also provided for at times supplying each section with "alternating train controlling current. Fvor this purpose each section is provided withfa train control transformer designated by the referencecharacter L with an exponent corresponding to the location and havingits secondary 8' conne,ct ed across the rails adjacent the'exit end of the corresponding section through an impedance 10. The'primary 9 of each transformer L? .that offthe .track circuit current from asuitv able source such as an alternator G. It follows that each track section is supplied with track circuit, current from a :track transformer T at all times, and that the rails of each section are further provided with alternating train controlling current "from the associated'transforiner Lwhen the tracli occupiessection 13 C, train controlling current from transformer L w'ould flow through secondary .5 of transformer" TC, thereby creating in primaryo oftransfor ner T v an alternating current of train control I In order to pre'ventJthis, I provide appar ratus for preventingtheflow of current from one of the transformers for each section through the secondary of the other tran sformer connected'with the same section. To

accomplish-this result 'I connect a rectifier.

12 of any suitable form in series withsecondary "5 of each transformer T, and 'a 1 similarlrectifier 14 in series with secondary 8 of each transformer 'L. Due to thereotifiers 12Qand 14, track circuit. current and train controlling current are supplied "to each section only during 'alternate' half transformer L and the associated rectifier 14, each rectifier 11 and 13 being so disposed as to oppose the flow of current from the associated transformer during the half cycle that current. is supplied from such transformer to the rails of the associated section. It will be seen that with this ar-- rangement, during each half cycle of train controlling current supplied to the rails by the transformer L, the current is of such poformer T in the low resistance direction.

larity as to be opposed by the rectifier 12 associated with the adjacent track trans- Furthermore current from a track transformer T is prevented from flowing through an adjacent train control transformer L by the associated rectifier 14. One purpose of the rectifiers 11 and 13 is to provide short circuitpaths for energy which might tend to'feed over from one transformer to another. Thus current tending to feed over from transformer L traverses rectifier 14: in its high resistance, direction, butthis current will be shunted by rectifier 13, the current flowing througlr13 in the low resistance direction. In similar manner this stray current will also flow through rectifier 11 associated with transformer T Similarly stray current tending to flow over from transformer T to transformer L will be shunted by the rectifiers 11 and 13.

Another purpose of the rectifiers 11 and 13 is to prevent improper operation should the associated series rectifier become shortcircuited. For example, if rectifier 14 as sociated with transformer L should become short-circuited, the rectifier would passtrain controlling current of the polarity normally suppressed but rectifiers 13 and 11 would shunt this current away from secondary 5 of transformer T thereby preventing the flow of such current to the line wires 3 and 3.

. It follows that with the apparatus em bodying my invention it is impossible for train controlling current to be supplied to tion except by train control transformer L associated with that section. Furthermore it is impossible for track circuit current to be supplied to the line wires which supply Having thus described my invention, what" I claim is:

1. In combination, a stretch of railway track, two sources of alternating current of different frequencies connected with the rails of said stretch, and two rectifiers one interposed between each source and a rail of the stretch for supplying current of the same polarity to the rails of thestretch from both sources. fl

In combination, a stretch of railway track comprising a plurality of successive track sections, a pair of line Wires extending throughout said stretch, a track transformer for each section having its secondary connected with the rails of the section and its primaryjconnected withsaid line wires, a source of train controlling current for each section for at times supplying current to the rails of the corresponding section, and means for preventing the flow'of train con trolling current in said line wires and in cluding rectifiers one interposed between each said track transformer and a rail and another interposed between each saidsource and a rail. V

3. In combination with a stretch of railway track, two transformers having their secondaries connected in parallel across the rails of said stretch, means for supplying alternating currents to the primaries of said transformers, and means for preventing current from either transformer from flowing through the other transformer and including two rectifiers one connected between each secondary and a rail of the stretch, and two other rectifiers one connected across each secondary and the rectifier associated therewith.

4:. In combination, a stretch of railway track, two transformers having their second aries connected in parallel across the rails of said stretch, means for supplying alternating currents of different frequencies to the primaries of said transformers, t-wo rectifiers one interposed between each transformer and a rail in such manner 'thatsaid transformers supply current to the rails during corresponding half cycles of such cur- SIS lea

cessive track sections, two sources of alter-.

nating current for each section connected in parallel with the rails of such section, and means comprising a rectifier interposed between each source and a rail of the associated section for preventing current from any source from flowing through the other source for the same section.

6. In combination, a stretch of railway track comprising a plurality of successive track sections, a first and a second pair of line wires extending throughout the stretch, a track transformer for each section having its primary connected with the first pair of line wires, a track relay for each section responsive to current in the associated track rails, a train control transformer for each section having its primary connected with the second pair of line wires over a front contact of the track relay for an adjacent section, the secondaries of the track transformer and the train control transformer for each section being connected in parallel across the rails of the corresponding section and a rectifier interposed between each secondary and a rail of the corresponding section for preventing current from any train control transformer from flowing through the secondary of the associated track transformer. I

7. In combination, a stretch of railway track, two sources of alternating current of different frequencies connected with the rails of said stretch, and two rectifiers one interposed between each source and a rail of the stretch for suppressing half cycles of the same relative polarity in the current from both sources.

8. In combination, a pair of conductors, two sources of alternating current of different frequencies connected with said conductors, and two rectifiers one interposed between each said source and one of said conductors for supplying current of the same polarity to the conductors fromboth sources. I i

9. In combination, a pair of conductors, two transformers having their secondaries connected in parallel across said conductors,

means for supplying alternating currents of I different frequencies to the primaries of said transformers, two rectifiers one interposed between each transformer and a conductor in such manner that the transformers supply current to the conductors during corresponding half cycles of such current and two other rectifiers one connected in parallel with each secondary and the associated rectifier and offering its higher resistance to current from the associated transformer during such half cycles.

In testimony whereof I affix my signature.

HOWVARD A. THOMPSON. 

